Sod harvester having auxiliary stacking conveyor

ABSTRACT

A sod harvester can include an auxiliary stacking conveyor for stacking or folding slabs of sod on a conveyor prior to the stacked/folded slabs being removed from a stacking conveyor by a stacking head. The auxiliary stacking conveyor can be configured to receive a leading slab of sod and then stack the leading slab on top of a trailing slab while the trailing slab is being advanced along a conveyor. The auxiliary stacking conveyor can also be configured to partially receive a slab of sod and then reverse direction to cause the slab to be folded backwards on top of itself while being advanced along a conveyor. Different configurations can be employed to cause slabs to be selectively positioned on an auxiliary stacking conveyor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/815,514 which was filed on Jul. 31, 2015.

U.S. patent application Ser. No. 13/851,402 (“the '402 application”)discloses techniques for accumulating multiple slabs of sod at a frontend of a stacking conveyor prior to advancing the stacking conveyor to aposition where the accumulated slabs are picked up. A sod harvesterconfigured in accordance with the present invention could also beconfigured to perform the accumulation techniques described in the '402application. Accordingly, the '402 application is incorporated herein byreference.

U.S. patent application Ser. No. 14/303,316 (“the '316 application”)discloses various techniques for controlling the movement of thestacking conveyor and/or stacking head to maximize the rate at which thestacking head can remove sod from the stacking conveyor. A sod harvesterconfigured in accordance with the present invention could also beconfigured to perform any of the techniques disclosed in the '316application. Accordingly, the '316 application is incorporated herein byreference.

BACKGROUND

Turf grass (sod) is a living organism that must be handled properly toensure its survival when it is removed from one location andtransplanted to another. Sod is generally harvested using largemachinery that cuts slabs of sod from the soil and stacks them onpallets.

FIG. 1 illustrates a portion of a sod harvesting machine 100 thatincludes a typical cutting head, conveyor system, and stacking system.The cutting head of FIG. 1 includes a chop mechanism 110, an oscillatingblade 103, and a roller 104. Chop mechanism 110 is configured toperiodically descend into the sod 151 to make vertical cuts defining aninitial width/length of the slabs. Oscillating blade 103 oscillates backand forth underneath the sod to sever the slab from the underlying soil150. Roller 103 applies pressure to the sod as it is cut to facilitatethe cutting of clean slabs. Slabs cut by the cutting head are routed toconveyor 101 which lifts the slabs up to stacking conveyor 102 fromwhich they are removed by a stacking head 105 for stacking on a pallet.Typically, the pallet is positioned adjacent to the stacking conveyor sothat the stacking head can move back and forth between the stackingconveyor and pallet when stacking.

It is generally desirable to harvest sod as quickly as possible.However, various factors limit the speed at which sod can be harvestedprimary of which is the rate at which sod can be stacked on a pallet.For example, the ground speed of the sod harvester directly defines therate at which sod is harvested. However, even if a sod harvester iscapable of cutting sod from the ground at a faster rate, the sodharvester may still be limited by the rate at which the sod can beremoved from the stacking conveyor and stacked on the pallet. In otherwords, the ground speed of sod harvester 100 is limited by the rate atwhich the stacking head 105 can remove sod from stacking conveyor 102.

Even if a stacking head can be operated quickly to increase the rate ofsod harvesting, the increased rate does not necessarily yield a net gainin efficiency. For example, operating the stacking head at high ratescan require substantial additional amounts of energy leading toincreased fuel costs. These increased fuel costs may offset any gainsresulting from the increased rate of sod harvesting. Also, operating athigh rates increases the forces on the components of the stacking headleading to more frequent and costly repairs and corresponding downtime.Accordingly, the stacking head oftentimes forms the bottleneck duringthe sod harvesting process.

BRIEF SUMMARY

The present invention extends to a sod harvester that includes anauxiliary stacking conveyor for stacking or folding slabs of sod priorto the stacked/folded slabs being removed from a stacking conveyor bythe stacking head. In this way, the stacking head can remove multiplelayers of sod during a single stacking operation. By removing multiplelayers of sod, the stacking head can move less frequently while stillstacking sod at the same rate. This results in reduced fuel consumptionand wear and tear on the stacking head while still enabling high ratesof harvesting.

In some embodiments, the auxiliary stacking conveyor can be configuredto receive a leading slab of sod and then stack the leading slab on topof a trailing slab while the trailing slab is being advanced along aninclined conveyor. In other embodiments, the auxiliary stacking conveyorcan be configured to partially receive a slab of sod and then reversedirection to cause the slab to be folded backwards on top of itselfwhile being advanced along an inclined conveyor. An inclined conveyorcan be configured in various ways to cause slabs to be selectivelyadvanced onto the auxiliary stacking conveyor including, for example, bypivoting the inclined conveyor, by employing a pivoting gate, or byemploying an auxiliary stacking head.

After slabs of sod have been stacked or folded on the conveyor, thestacked slabs can be advanced onto the stacking conveyor to a positionwhere the stacking head can remove the stacked or folded slabs for finalstacking on a pallet. In some embodiments, stacked or folded slabs canbe accumulated on the stacking conveyor prior to being advanced to theposition where they will be removed from the stacking conveyor.

In one embodiment, the present invention is implemented as a sodharvester comprising a cutting head for cutting slabs of sod from theground, a stacking conveyor, a stacking head positioned overtop thestacking conveyor, a first inclined conveyor for receiving the slabsfrom the cutting head, a second inclined conveyor positioned between thefirst inclined conveyor and the stacking conveyor, and an auxiliarystacking conveyor positioned overtop the second inclined conveyor. Theauxiliary stacking conveyor is configured to form stacks of slabs on thesecond inclined conveyor prior to the stacks of slabs being advanced tothe stacking conveyor. The stacking head is configured to remove thestacks of slabs from the stacking conveyor.

In another embodiment, the present invention is implemented as a sodharvester comprising a cutting head for cutting slabs of sod from theground, a stacking conveyor, a stacking head positioned overtop thestacking conveyor, one or more inclined conveyors for advancing theslabs of sod from the cutting head to the stacking conveyor, anauxiliary stacking conveyor positioned overtop the one or more inclinedconveyors, and an auxiliary stacking head configured to selectivelyremove the slabs from the one or more inclined conveyors and place theslabs on the auxiliary stacking conveyor. The auxiliary stackingconveyor is configured to form stacks of slabs on the one or moreinclined conveyors prior to the stacks of slabs being advanced to thestacking conveyor. The stacking head is configured to remove the stacksof slabs from the stacking conveyor.

In another embodiment, the present invention is implemented as a methodfor harvesting sod. Slabs of sod are cut from the ground. The slabs areadvanced along one or more inclined conveyors that carry the slabs fromthe ground to a stacking conveyor. Prior to advancing the slabs onto thestacking conveyor, stacks of two or more slabs are formed on the one ormore inclined conveyors. The stacks of slabs are advanced onto thestacking conveyor. The stacks of slabs are then removed from thestacking conveyor.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by the practice of the invention. Thefeatures and advantages of the invention may be realized and obtained bymeans of the instruments and combinations particularly pointed out inthe appended claims. These and other features of the present inventionwill become more fully apparent from the following description andappended claims, or may be learned by the practice of the invention asset forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the above-recited and otheradvantages and features of the invention can be obtained, a moreparticular description of the invention briefly described above will berendered by reference to specific embodiments thereof which areillustrated in the appended drawings. Understanding that these drawingsdepict only typical embodiments of the invention and are not thereforeto be considered to be limiting of its scope, the invention will bedescribed and explained with additional specificity and detail throughthe use of the accompanying drawings in which:

FIG. 1 illustrates an example of various components of a typical sodharvesting machine;

FIG. 2 illustrates an example of a sod harvester that includes anauxiliary stacking conveyor that is positioned overtop an inclinedconveyor;

FIGS. 3A and 3B illustrate an embodiment of a sod harvester where asecond inclined conveyor and the auxiliary stacking conveyor pivotbetween a raised and lowered position to selectively advance slabs ofsod from the first conveyor onto either the auxiliary stacking conveyoror the second inclined conveyor;

FIGS. 4A and 4B illustrate an embodiment of a sod harvester where afirst inclined conveyor pivots between a raised and a lowered positionto selectively advance slabs of sod from the first inclined conveyoronto either the auxiliary stacking conveyor or the second inclinedconveyor;

FIGS. 5A and 5B illustrate an embodiment of a sod harvester where a gatepositioned between a first inclined conveyor and a second inclinedconveyor pivots between a raised and a lowered position to selectivelyadvance slabs of sod from the first conveyor onto either the auxiliarystacking conveyor or the second inclined conveyor;

FIGS. 6A-6J illustrate a sequence of views of the sod harvester of FIGS.4A and 4B depicting how the auxiliary stacking conveyor stacks slabs ofsod on an inclined conveyor prior to the stacked slabs being advancedonto the stacking conveyor;

FIG. 7 illustrates an embodiment of a sod harvester that includes anauxiliary stacking conveyor and an auxiliary stacking head for placingslabs on sod on the auxiliary stacking conveyor;

FIGS. 7A-7H illustrate a sequence of views of the sod harvester of FIG.7 depicting how the auxiliary stacking head and auxiliary stackingconveyor operate to stack slabs of sod in an inverted manner on theinclined conveyor;

FIGS. 8A-8F illustrate a sequence of views of the sod harvester of FIGS.4A and 4B when the auxiliary stacking conveyor is configured to foldslabs of sod on the inclined conveyor;

FIGS. 9A and 9B each illustrates the sod harvester of FIG. 2 along witha sensor that could be employed to implement proper timing of theauxiliary stacking conveyor; and

FIGS. 9C and 9D represent how the sensor shown in FIG. 9B can detect amisalignment in stacked or folded slabs.

DETAILED DESCRIPTION

FIG. 2 illustrates components of a sod harvester 200 that is configuredin accordance with embodiments of the present invention. Although notshown, sod harvester 200 would include a cutting head for removing slabsof sod from the ground and delivering the slabs to a first inclinedconveyor 201 a. Sod harvester 200 also includes a second inclinedconveyor 201 b that is positioned between first inclined conveyor 201 aand stacking conveyor 202.

First and second inclined conveyors 201 a, 201 b can preferably beoperated at a speed that is slightly faster than ground speed so that agap exists between each slab of sod as the slabs travel along theinclined conveyors. A stacking head 205 can be employed to remove theslabs of sod from stacking conveyor 202 and to stack the slabs on apallet. Typically, the pallet can be positioned alongside stackingconveyor 202; however, the position of the pallet is not essential tothe invention. Examples of stacking head 205 and its operation aredisclosed in the '316 application as well as in U.S. Pat. No. 9,022,720titled “Electrically Operated Turf Stacking System For Sod HarvestingMachine” which is incorporated herein by reference. The presentinvention, however, should not be limited to any particularconfiguration of stacking head 205 as long as stacking head 205 isconfigured to pick up stacked or folded slabs of sod as will be furtherdescribed below.

In accordance with embodiments of the present invention, sod harvester200 also includes an auxiliary stacking conveyor 206 which is used tostack or fold slabs of sod on inclined conveyor 201 b (and, in somecases, at least partially on inclined conveyor 201 a). Auxiliarystacking conveyor 206 is positioned above second inclined conveyor 201 band is configured to receive slabs of sod to be stacked or folded. A sodharvester that includes an auxiliary stacking conveyor can be configuredin various different ways to form stacked or folded slabs of sod onsecond inclined conveyor 201 b.

FIGS. 3A and 3B depict an embodiment of a sod harvester 300 in whichsecond inclined conveyor 201 b and auxiliary stacking conveyor 206 arepivoted between a raised and a lowered position (as represented by thearrow) to allow slabs of sod to be advanced from first inclined conveyor201 a onto either second inclined conveyor 201 b or auxiliary stackingconveyor 206. In FIG. 3A, second inclined conveyor 201 b and auxiliarystacking conveyor 206 are in the raised position. In this raisedposition, slabs of sod advancing on first inclined conveyor 201 a willcontinue onto second inclined conveyor 201 b. In contrast, in FIG. 3B,second inclined conveyor 201 b and auxiliary stacking conveyor 206 arein the lowered position. In this lowered position, slabs of sodadvancing on first inclined conveyor 201 a will continue onto auxiliarystacking conveyor 206.

FIGS. 4A and 4B depict an embodiment of a sod harvester 400 in whichfirst inclined conveyor 201 a is pivoted between a raised and loweredposition (as represented by the arrow) to allow slabs of sod to beadvanced onto either second inclined conveyor 201 b or auxiliarystacking conveyor 206. In this embodiment, FIG. 4A represents thelowered position, while FIG. 4B represents the raised position of firstinclined conveyor 201 a.

FIGS. 5A and 5B depict an embodiment of a sod harvester 500 in which agate 501 is positioned between first inclined conveyor 201 a and secondinclined conveyor 201 b. Gate 501 can pivot between a raised position(shown in FIG. 5B) and a lowered position (shown in FIG. 5A). When inthe raised position, gate 501 will cause slabs of sod to be advancedfrom first inclined conveyor 201 a onto auxiliary stacking conveyor 206.In contrast, when in the lowered position, gate 501 will cause slabs ofsod to be advanced onto second inclined conveyor 201 b.

Although not depicted, in some embodiments, each of the conveyors maypivot to cause proper alignment in the conveyors. For example, to reachthe configuration shown in FIGS. 3B and 4B, first inclined conveyor 201a may pivot upwardly while auxiliary stacking conveyor 206 may pivotdownwardly. Similarly, to reach the configuration shown in FIG. 5B, gate501 may pivot upwardly while auxiliary stacking conveyor 206 may pivotdownwardly. Accordingly, the particular manner in which the sodharvester toggles between routing slabs to second inclined conveyor 201b and to auxiliary stacking conveyor 206 is not essential to theinvention.

In any of these embodiments, alternate slabs of sod can be advanced ontoauxiliary stacking conveyor 206 to allow such slabs to be stacked oncorresponding trailing slabs. This process of stacking slabs usingauxiliary stacking conveyor 206 is illustrated in FIGS. 6A-6J using sodharvester 400 as an example. It is noted, however, that the process ofstacking slabs would be performed in substantially the same manner bysod harvester 300, sod harvester 500, or another similarly configuredsod harvester.

In general, auxiliary stacking conveyor 206 functions as a buffer fortemporarily storing a slab that is to be stacked on top of a trailingslab. Accordingly, each leading slab can be advanced onto auxiliarystacking conveyor 206 (either by pivoting first inclined conveyor 201 asshown in FIGS. 6A-6J, by pivoting second inclined conveyor 201 b andauxiliary stacking conveyor 206, by pivoting gate 501, or by somecombination of these functions).

FIG. 6A represents a state of operation in which slabs of sod arebeginning to be cut from the ground and advanced onto first inclinedconveyor 201 a. Because no slab is positioned on top of auxiliarystacking conveyor 206, first inclined conveyor 201 a is in the raisedposition so that a leading slab, slab 301 a, will be advanced ontoauxiliary stacking conveyor 206.

FIG. 6B illustrates that slab 301 a has been advanced onto auxiliarystacking conveyor 206 where it will be maintained (e.g., by stoppingauxiliary stacking conveyor 206) to await a trailing slab, slab 301 b.Once slab 301 a has been advanced onto auxiliary stacking conveyor 206,first inclined conveyor 201 a is returned to the lowered position sothat slab 301 b will be advanced onto second inclined conveyor 201 b asshown in FIG. 6C. During this pivoting, first inclined conveyor 201 acan continue to rotate to cause slab 301 c to be advanced onto firstinclined conveyor 201 a.

As shown in FIG. 6D, once slab 301 b has been advanced onto secondinclined conveyor 201 b, first inclined conveyor 201 a can again bepivoted into the raised position. First inclined conveyor 201 a cancontinue rotating during this upward pivoting. FIG. 6D also shows that,as slab 301 b continues advancing along second inclined conveyor 201 b,auxiliary stacking conveyor 206 can commence rotating to cause slab 301a to be advanced on top of slab 301 b. In this way, a set of stackedslabs is formed on second inclined conveyor 201 b with slab 301 a, theleading slab, being stacked on top of slab 301 b, the trailing slab, asshown in FIG. 6E.

This preliminary stacking process can continue on subsequent slabs. Forexample, as shown in FIG. 6E, slab 301 c can be advanced onto auxiliarystacking conveyor 206. Second inclined conveyor 201 b can continue toadvance the set of stacked slabs 301 a, 301 b towards stacking conveyor202. With slab 301 c advanced onto auxiliary stacking conveyor 206,first inclined conveyor 201 a can pivot downwardly to feed slab 301 donto second inclined conveyor 201 b. The continued rotation of secondinclined conveyor 201 b can cause the set of stacked slabs 301 a, 301 bto reach stacking conveyor 202 which may also be rotated to cause theset of stacked slabs to be positioned towards a front end of thestacking conveyor. Stacking conveyor 202 may be stopped in this positionto allow multiple sets of stacked slabs to be accumulated on stackingconveyor 202 in accordance with the techniques described in the '402application.

FIG. 6G illustrates that a second set of stacked slabs 301 c, 301 d isformed on second inclined conveyor 201 b as described above. This secondset of stacked slabs 301 c, 301 d can be advanced towards stackingconveyor 202 as shown in FIG. 6H as the preliminary stacking processcontinues on slabs 301 e, 301 f, 301 g, etc.

FIG. 6I represents that the second set of stacked slabs 301 c, 301 d hasreached the first set of stacked slabs 301 a, 301 b. At this moment,stacking conveyor 202 can be advanced to cause the accumulated sets ofstacked slabs to be positioned underneath stacking head 205 which cansimultaneously remove the two sets of stacked slabs from stackingconveyor 202 for stacking on a pallet.

In this example, it will be assumed that stacking head 205 is configuredto remove two sets of stacked slabs (i.e., four slabs) at a time.However, stacking head 205 could also be configured to remove any numberof sets of stacked slabs (e.g., three sets or six total slabs) at a timedepending on the dimensions of the slabs. In any case, once theappropriate number of sets of stacked slabs is accumulated on stackingconveyor 202, the stacking conveyor can be advanced to position the setsof stacked slabs underneath stacking head 205.

Stacking head 205 can secure both layers of the stacked slabs in anysuitable manner such as by piercing through both layers. Suitableexamples of a stacking head 205 are described in the '316 application.Additionally, the techniques described in the '316 application forcontrolling movement of the stacking conveyor and/or stacking head canbe used to further increase the rate at which stacking head 205 canremove slabs from stacking conveyor 202.

Because stacking head 205 removes two layers of slabs with each stackingoperation, stacking head 205 effectively doubles the number of slabsthat are stacked with each stacking operation. Accordingly, the stackingoperation does not need to be performed as frequently as when a singlelayer is stacked at a time. Given that the stacking operation isoftentimes the bottleneck during the harvesting process, the presentinvention can allow the sod harvester to be operated at greater groundspeeds.

Further, although stacking double the amount of slabs increases theamount of energy that is required to perform a single stacking operation(e.g., due to the increased weight that stacking head 205 must move),the reduction in the number of stacking operations that must beperformed provides a net energy savings. Therefore, the presentinvention provides benefits in the form of efficiency and yield.

In the above described embodiments, the slabs of sod are stacked in adirt-to-grass orientation (i.e., both slabs in the stack are orientedwith the grass side up). However, in some embodiments, it may bedesirable to stack the slabs in a grass-to-grass orientation (i.e., withthe top slab being oriented with the grass side down and the bottom slabbeing oriented with the grass side up). FIG. 7 illustrates an embodimentof a sod harvester 700 that is configured to allow slabs to be stackedin this grass-to-grass orientation.

Sod harvester 700, as with the previously described sod harvesters,includes an auxiliary stacking conveyor 206. Additionally, sod harvester700 includes an auxiliary stacking head 215 and inverting guides 216.Auxiliary stacking head 215 is configured to pick up slabs of sod frominclined conveyor 201, after the slabs have passed under auxiliarystacking conveyor 206, and place them on top of auxiliary stackingconveyor 206. Accordingly, auxiliary stacking head 215 can be configuredto move in a generally up and down and forward and backward direction asindicated by the arrows in FIG. 7. It is noted that, in someembodiments, auxiliary stacking head 215 could be positioned prior toauxiliary stacking conveyor 206. However, regardless of where auxiliarystacking head 215 is positioned with respect to auxiliary stackingconveyor 206, its function can be substantially the same as describedbelow.

Once auxiliary stacking head 215 places a slab on auxiliary stackingconveyor 206, auxiliary stacking conveyor 206 can be rotated in adirection opposite the rotation of inclined conveyor 201 (i.e., in aclockwise direction in FIG. 7) to cause the slab to be dropped off thefront edge of auxiliary stacking conveyor 206. Inverting guides 216 canbe positioned to cause the rear (or right) edge of the slab to rotate ina clockwise direction thereby causing the slab to invert on top of atrailing slab. Inverting guides 216 can be any structure capable ofguiding this inversion of the slab as it descends from auxiliarystacking conveyor 206. Although sod harvester 700 is shown as includingtwo inverting guides 216, any number of inverting guides, including asingle inverting guide, could be employed. This process of stackingslabs in the grass-to-grass orientation is depicted in FIGS. 7A-7H.

In FIG. 7A, a leading slab, slab 301 a, and a trailing slab, slab 301 b,are shown advancing along inclined conveyor 201. As slab 301 a ispositioned underneath auxiliary stacking head 215, the auxiliarystacking head descends to pick up the slab. Then, as shown in FIG. 7B,auxiliary stacking head 215 moves overtop auxiliary stacking conveyor206 to place slab 301 a on top of auxiliary stacking conveyor 206. Slab301 a can remain on top of auxiliary stacking conveyor 206 until acorresponding slab, which is slab 301 c in this example, has beenadvanced to the proper position on inclined conveyor 201.

As shown in FIG. 7C, after placing slab 301 a on auxiliary stackingconveyor 206, auxiliary stacking head 215 returns to pick up slab 301 b.As also shown in FIG. 7C, as slab 301 c reaches the appropriate positionon inclined conveyor 201, auxiliary stacking conveyor 206 can beadvanced to cause slab 301 a to be inverted on top of slab 301 c. Theposition of inverting guides 216 causes the rear (or right) edge of slab301 a to rotate clockwise so that slab 301 a will be positioned with itsgrass side facing down.

FIG. 7D illustrates that the stack of slabs 301 a, 301 c continues toadvance along inclined conveyor 201 as slab 301 b is placed on top ofauxiliary stacking conveyor 206. As shown in FIG. 7E, after placing slab301 b on auxiliary stacking conveyor 206, auxiliary stacking head 215can return to its base position to await the next slab. As slab 301 dreaches the appropriate position, auxiliary stacking conveyor 206 canadvance slab 301 b to invert it on top of slab 301 d.

During this process, inclined conveyor 201 can be continuously rotated.Accordingly, the stack of slabs 301 a, 301 c and the stack of slabs 301b, 301 d are advanced towards and onto stacking conveyor 202 as shown inFIGS. 7F and 7G. Also, this continuous rotation of inclined conveyor 201causes slabs 301 e and 301 f to advance towards auxiliary stacking head215.

Once slab 301 e reaches the appropriate position, auxiliary stackinghead 215 descends to pick up the slab to continue the process depictedin FIGS. 7A-7G. As represented in FIG. 7H, stacking conveyor 202 can beconfigured to accumulate two or more stacks of slabs prior topositioning the stacks underneath stacking head 205 in accordance withthe techniques described in the '402 application.

As can be seen in these figures, a slab can be stacked in an upside-downmanner on top of another slab. To facilitate stacking slabs in thismanner without slowing the ground speed of the sod harvester, a slab canbe stacked, not on an immediately trailing slab, but on the nextfollowing slab (e.g., a first slab could be stacked on a third slab, asecond slab could be stacked on a fourth slab, etc.). However, it isnoted that it is not necessary to pick up two consecutive slabs forstacking on two other consecutive slabs. The exact pattern with whichslabs are handled can vary based on various factors including the rateat which slabs pass under auxiliary stacking conveyor 206, the distancebetween auxiliary stacking head 215 and auxiliary stacking conveyor 206,an amount of time required to pick up a slab and place it on auxiliarystacking conveyor 206, whether a slab has already been picked up orplaced on auxiliary stacking conveyor 206, etc.

Each of the above described embodiments can be implemented to formstacks of multiple slabs on an inclined conveyor of a sod harvester.However, in some embodiments, it may be preferable to form a “stack”from a single slab of sod. In other words, a single long slab of sodcould be folded in half to create a stack with a grass-to-grassorientation. Such folded slabs will hereafter be referred to as “foldedstacks.”

Any sod harvester 200 having an auxiliary stacking conveyor 206positioned overtop a second inclined conveyor 201 b could be employed toform folded stacks on an inclined conveyor including the embodiments ofsod harvester 200, 300, and 400 described above. For example, FIGS.8A-8F illustrate how auxiliary stacking conveyor 206 can be employed toform folded stacks in an embodiment of sod harvester 400.

FIGS. 8A and 8B illustrate that first inclined conveyor 201 a caninitially be in the raised position to feed a slab 301 a partially ontoauxiliary stacking conveyor 206. Once slab 301 a has advanced partiallyonto auxiliary stacking conveyor 206, first inclined conveyor 201 a canbe dropped into the lowered position as shown in FIG. 8C. As it isdropped, first inclined conveyor 201 a can continue to rotate while therotation of auxiliary stacking conveyor 206 can be reversed. Thereversing of auxiliary stacking conveyor 206 along with the continuedadvancement of first inclined conveyor 201 a causes the front half ofslab 301 a to fold backwards on top of the back half of slab 301 a asshown in FIG. 8D. In this way, slab 301 a forms a folded stack oninclined conveyor 201 b.

As shown in FIGS. 8E and 8F, slab 301 a advances as a folded stack ontostacking conveyor 202 while a subsequent slab 301 b advances ontoauxiliary stacking conveyor 206 to again initiate the folding process.This folding of slabs could be accomplished in substantially the samemanner when implemented on sod harvester 300 (e.g., by pivoting secondinclined conveyor 201 b and auxiliary stacking conveyor 206) and sodharvester 500 (e.g, by pivoting gate 501).

In order to operate auxiliary stacking conveyor 206 (as well asauxiliary stacking head 215) with the appropriate timing, a sodharvester may include one or more sensors. FIG. 9A illustrates anexample of how a sensor 207 could be positioned overtop first inclinedconveyor 201 a prior to auxiliary stacking conveyor 206. Of course, oneor more sensors 207 could alternatively or additionally be positioned inother locations (e.g., to the side of first inclined conveyor 201 a) toperform similar functions as will be described. In this example, sensor207 could be an optical sensor that senses the leading and/or trailingedge of a slab of sod as the slab travels along first inclined conveyor201. Other positions and/or types of sensors could alternatively oradditionally be provided. For example, a sensor may be positionedovertop auxiliary stacking conveyor 206. In short, any sensor or sensorsthat can be used to identify the position of a slab of sod on firstinclined conveyor 201 a (or inclined conveyor 201 in sod harvester 700)and/or on auxiliary stacking conveyor 206 could be used.

Based on input from sensor 207, a control unit (not shown) couldcalculate when a slab will be appropriately positioned for advancementonto auxiliary stacking conveyor 206 or for pickup by auxiliary stackinghead 215. For example, the control unit could be configured to receiveinput from sensor 207 indicative of when the leading and trailing edgesare sensed. Based on this input (and assuming the control unit knows thedimensions of the slab), the control unit could calculate the speed atwhich first inclined conveyor 201 a (or similarly the speed at whichsecond inclined conveyor 201 b or inclined conveyor 201) is operating.Based on a calculated speed, the control unit could determine when aslab will reach the end of first inclined conveyor 201 a or reach aposition underneath auxiliary stacking head 215. Alternatively, if thespeed of an inclined conveyor is a known parameter (e.g., based on inputfrom another sensor), the control unit could be configured to receiveinput from sensor 207 indicative of a single edge of the slab (i.e., ofeither the leading or trailing edge) and from such input identify whento perform proper adjustments to the sod harvester.

These adjustments will vary based on the particular embodiment employed.For example, in sod harvester 300, input from sensor 207 could be usedto control the timing of the pivoting of the conveyors as well as thetiming and/or speed of rotation of auxiliary stacking conveyor 206 (bothto advance a slab onto the conveyor and to advance a slab off theconveyor). Similarly, with sod harvester 400, input from sensor 207could be used to control when first inclined conveyor 201 a is pivotedand to control the timing and/or speed of rotation of auxiliary stackingconveyor 206. With sod harvester 500, input from sensor 207 could beemployed to control when gate 501 pivots and when auxiliary stackingconveyor 206 is rotated. In summary, in any of these cases, the inputfrom sensor 207 can be used to calculate proper timing to ensure that aslab is stacked on top of another slab.

Similarly, input from sensor 207 could be employed to control the timingof operation of auxiliary stacking head 215 in sod harvester 700. Thisinput could also be used to control when auxiliary stacking conveyor 206rotates to ensure that a slab is properly inverted on top of a trailingslab.

Further, in embodiments where folded stacks are formed, input fromsensor 207 could be employed to control when auxiliary stacking conveyor206 reverses its rotation. In particular, this input could be used tocalculate when the slab's direction should be reversed to ensure thatthe slab folds in half. This calculation could vary based on a number offactors (some of which may be dynamically determined) such as the watercontent of the slab, the type of grass, the type of soil, or any othermeasurable factor that may affect how a slab will fold.

FIG. 9B illustrates an example of how a sensor 208 could be positionedafter auxiliary stacking conveyor 206 (e.g., overtop second inclinedconveyor 201 b or stacking conveyor 202). Sensor 208 could be used toverify whether slabs are being stacked in alignment and could be usedalone or in conjunction with sensor 207 to monitor proper operation ofthe stacking or folding operation.

If slabs were stacked out of alignment, sensor 208 could detect themisalignment in either the leading edges or the trailing edges of theslabs. In cases where folded stacks are formed, misalignment could bedetected at the trailing (or non-folded) edges. FIGS. 9C and 9Dillustrate instances where the top slab is advanced off of auxiliarystacking conveyor 206 too soon and too late respectively. In each ofFIGS. 9C and 9D, two stacked slabs are represented as moving from rightto left along the top surface of second inclined conveyor 201 b (orequally along inclined conveyor 201 or stacking conveyor 202) as theypass under sensor 208 (represented in dashed lines). Whenever slabs arestacked in misalignment, sensor 208 (which can preferably be an opticalsensor) can identify the misalignment by detecting a three-steptransition as the stacked slabs pass under the sensor.

In FIG. 9C, because the top slab was released too soon, the leading edgeof the top slab overlaps the leading edge of the bottom slab. Therefore,as the stacked slabs pass under sensor 208, the sensor will detect afirst transition from the top surface of second inclined conveyor 201 bto the top surface of the top slab. In FIG. 9C, this first transition isrepresented as occurring at time t₁. Then, due to the misalignment,sensor 208 will detect a second transition from the top surface of thetop slab to the top surface of the bottom slab. This second transitionis represented as occurring at time t₂. Shortly thereafter, sensor 208will detect a third transition from the top surface of the bottom slabto the top surface of second inclined conveyor 201 b. This thirdtransition is represented as occurring at time t₃.

In FIG. 9D, because the top slab was released too late, the trailingedge of the top slab overlaps the trailing edge of the bottom slab. Inthis case, sensor 208 will still detect a three-step transition in asimilar manner as described above; however, the spacing of thetransitions will differ. In particular, in the case depicted in FIG. 9D,the second transition occurs shortly after the first transition. Ofcourse, if the slabs are perfectly aligned, sensor 208 would only detecttwo transitions.

A control unit can be configured to process signals received from sensor208 indicative of the occurrence of these transitions and cause theoperation of auxiliary stacking conveyor 206 to be updatedappropriately. For example, if sensor 208 provides signals indicative ofa two-step transition (i.e., indicative that the slabs are aligned), thecontrol unit can continue to operate auxiliary stacking conveyor 206with the same timing. However, if sensor 208 provides signals indicativeof a three-step transition, the control unit can process the signals toidentify whether the top slab is being released too early or too late.For example, by comparing the amount of time between the first andsecond transitions to the amount of time between the second and thirdtransitions, the control unit can determine how the slabs aremisaligned. In particular, if the amount of time between the first andsecond transitions is greater than the amount of time between the secondand third transitions (as represented in FIG. 9C), the control unit candetermine that the top slab is being released too early. Further, insuch cases, the amount of time between the second and third transitionscan be used to identify how early the top slab is being released (e.g.,with reference to the speed of the inclined conveyor as determined bysensor 207 or another sensor). Similarly, if the amount of time betweenthe first and second transitions is less than the amount of time betweenthe second and third transitions (as shown in FIG. 9D), the control unitcan determine that the top slab is being released too late. Further, insuch cases, the amount of time between the first and second transitionscan be used to identify how late the top slab is being released. Ineither case, whenever the amount of time between the correspondingtransitions exceeds some threshold, the control unit can update thetiming of the operation of auxiliary stacking conveyor 206 to attempt tobetter align subsequently stacked slabs.

In one particular example, the control unit may employ a timing offsetto control the operation of auxiliary stacking conveyor 206 withreference to a signal from sensor 207. For example, when receiving asignal from sensor 207 identifying the leading edge of a slab, thecontrol unit may employ the timing offset to determine the time whenauxiliary stacking conveyor 206 should be advanced to drop a slab on topof another slab (e.g., 0.2 ms after detecting the leading edge). Basedon feedback from sensor 208, the control unit may update this timingoffset to ensure that slabs remain in alignment.

It is noted that with folded stacks it may not be possible to detect athree-step transition when the top portion of the folded slab overlapsthe bottom portion. In particular, if sensor 208 is positioned abovesecond inclined conveyor 201 b, it will only be able to detect thefolded edge and the overlapped top edge. In such cases, it may not bepossible to determine whether the slab is folded in perfect alignment orwhether the top is overlapping.

To address this difficulty without requiring additional sensors orcircuitry, the timing offset may be biased in one direction. Forexample, the control unit may be configured to cause the timing offsetto slowly decrease over time such that slabs are folded earlier overtime (i.e., the reversing of auxiliary stacking conveyor 206 could occursooner over time). This would cause the slabs to become misaligned inthe manner depicted in FIG. 9C (i.e., with the bottom portionoverlapping). This biasing could also be used in non-folding embodimentsbut is not necessary given the ability to detect a three-step transitionwhenever misalignment occurs.

Feedback from sensor 208 could be employed to ensure that the amount ofmisalignment remains within reasonable limits. In other words, thetiming of the operation of auxiliary stacking conveyor 206 can include abuilt-in bias towards early folding of a slab to ensure that the bottomportion is slightly overlapping, or in other words, to ensure thatsensor 208 will be able to detect both the top and bottom edges of thefolded slab. Feedback from sensor 208 can then be used to periodicallycorrect for the bias (e.g., by increasing the timing offset by asuitable amount if the overlap grows too large).

As stated above, this biasing technique could also be employed innon-folding embodiments. One benefit of employing this approach in anon-folding embodiment is that it can minimize the number of sensorsand/or the complexity of the timing algorithm. In particular, the biascan ensure that there is always a detectable amount of misalignment atthe trailing edges (e.g., that t₃−t₂≠0) and therefore, the control unitdoes not need to be configured to detect whether misalignment on theleading edge is occurring (i.e., the control unit will always know thatthe top slab is not being dropped too late and only needs to ensure thatthe misalignment on the trailing edges does not grow too big). This sametechnique could be used to ensure that misalignment always exist on theleading edge in non-folding embodiments. In other words, the built-inbias could cause the timing offset to slowly increase over time.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

What is claimed:
 1. A sod harvester comprising: a cutting head forcutting slabs of sod from the ground; a stacking conveyor; a stackinghead positionable overtop the stacking conveyor; a first inclinedconveyor for receiving the slabs from the cutting head; a secondconveyor positioned between the first inclined conveyor and the stackingconveyor; and an auxiliary stacking conveyor positioned overtop thesecond conveyor, the auxiliary stacking conveyor being configured toform stacks of slabs on the second conveyor prior to the stacks of slabsbeing advanced to the stacking conveyor by advancing a first slab fromthe first inclined conveyor onto the auxiliary stacking conveyor andthen advancing the first slab off the auxiliary stacking conveyor onto asecond slab as the second slab is advanced along the second conveyor inthe same direction as the first slab, the stacking head being configuredto remove the stacks of slabs from the stacking conveyor, wherein thestacks of slabs are formed on the second conveyor by performing one of:pivoting the first inclined conveyor to advance the first slab onto theauxiliary stacking conveyor and to advance the second slab onto thesecond conveyor; pivoting the second conveyor and the auxiliary stackingconveyor to cause the first slab to be advanced onto the auxiliarystacking conveyor and to cause the second slab to be advanced onto thesecond conveyor; or employing a gate that is positioned between thefirst inclined conveyor and the second conveyor, the gate beingconfigured to pivot to cause the first slab to be advanced onto theauxiliary stacking conveyor and to cause the second slab to be advancedonto the second conveyor.
 2. The sod harvester of claim 1, furthercomprising: one or more sensors positioned prior to the auxiliarystacking conveyor, the one or more sensors configured to generate one ormore signals when an edge of the slabs of sod is detected.
 3. The sodharvester of claim 2, further comprising: a control unit for controllingthe auxiliary stacking conveyor based on the one or more signalsreceived from the one or more sensors.
 4. The sod harvester of claim 3,wherein the control unit is configured to modify a timing of operationof the auxiliary stacking conveyor when misalignment is identified. 5.The sod harvester of claim 4, wherein modifying the timing of operationof the auxiliary stacking conveyor comprises modifying a timing offset.6. The sod harvester of claim 5, wherein the timing offset is biased. 7.The sod harvester of claim 1, wherein the second conveyor is inclined.8. A sod harvester comprising: a cutting head for cutting slabs of sodfrom the ground; a stacking conveyor; a stacking head positionableovertop the stacking conveyor; a set of one or more conveyors foradvancing the slabs of sod from the cutting head to the stackingconveyor; an auxiliary stacking conveyor positioned overtop the set ofone or more conveyors; and an auxiliary stacking head configured toselectively remove the slabs from the set of one or more conveyors andplace the slabs on the auxiliary stacking conveyor; wherein theauxiliary stacking conveyor is configured to form stacks of slabs on theset of one or more conveyors prior to the stacks of slabs being advancedto the stacking conveyor, the stacking head being configured to removethe stacks of slabs from the stacking conveyor.
 9. The sod harvester ofclaim 8, wherein the auxiliary stacking conveyor is configured to formstacks of slabs in a grass-to-grass orientation by advancing a firstslab, that is placed on the auxiliary stacking conveyor by the auxiliarystacking head, off of the auxiliary stacking conveyor while invertingthe first slab such that the first slab is placed on top of a secondslab as the second slab advances along the set of one or more conveyors.10. The sod harvester of claim 9, wherein the auxiliary stackingconveyor advances the first slab by rotating in a direction that isopposite a direction of rotation of the set of one or more conveyors.11. The sod harvester of claim 9, further comprising: one or moreinverting guides that are positioned alongside the auxiliary stackingconveyor to guide the inversion of the first slab.
 12. The sod harvesterof claim 8, wherein the set of one or more conveyors includes a firstinclined conveyor for receiving the slabs from the cutting head and asecond conveyor positioned between the first inclined conveyor and thestacking conveyor.
 13. The sod harvester of claim 12, wherein the secondconveyor is inclined.
 14. The sod harvester of claim 8, wherein the setof one or more conveyors includes a single inclined conveyor.
 15. Amethod for harvesting sod, the method comprising: cutting slabs of sodfrom the ground; advancing the slabs along a first inclined conveyorthat carry the slabs from the ground towards a second conveyor that ispositioned between the first inclined conveyor and a stacking conveyor;selectively diverting some of the slabs onto an auxiliary stackingconveyor that is positioned overtop the second conveyor, selectivelydiverting comprising one of: pivoting the first inclined conveyor;pivoting the second conveyor and the auxiliary stacking conveyor;pivoting a gate that is positioned between the first inclined conveyorand the second conveyor; or using a stacking head to pick up thediverted slabs and place the diverted slabs on the auxiliary stackingconveyor; for each diverted slab, advancing the diverted slab off theauxiliary stacking conveyor and onto one of the slabs that was notdiverted and that is being advanced along the second conveyor to therebyform a stack of slabs on the second conveyor; advancing each stack ofslabs from the second conveyor onto the stacking conveyor; and removingthe stacks of slabs from the stacking conveyor.
 16. The method of claim15, further comprising: modifying a timing of operation of the auxiliarystacking conveyor upon detecting that one or more stacks of slabs aremisaligned on the second conveyor.
 17. The method of claim 16, whereinthe misalignment is detected based on one or more signals received fromone or more sensors that detect edges of the slabs.
 18. The method ofclaim 16, wherein modifying the timing of operation comprises adjustinga timing offset.
 19. The method of claim 18, wherein the timing offsetis biased.
 20. The method of claim 15, wherein the second conveyor isnot stopped while each diverted slab is advanced onto one of the slabsthat was not diverted.